This invention relates in general to mobility vehicles, and more particularly to wheelchair seating. The most basic wheelchair seating surface is the sling. Many wheelchair users sit directly on a sling, while others sit on a cushion atop a sling. Sitting directly on a sling is not advisable, as it does not provide for an adequate distribution of the user's body weight, and it encourages postural asymmetries, such as pelvic obliquity and internal hip rotation, as illustrated in FIG. 1. Many wheelchair users also slide forward while sitting directly on the sling upholstery, causing increased pressure in the sacral region and placing them at risk of sliding out of the wheelchair. Additionally, users sitting directly on the sling often experience high pressure on the areas of bony prominence, such as the ischial tuberosities and coccyx. High pressure in these areas increases the risk of skin wounds, such as pressure ulcers. In FIG. 2, there is illustrated a measurement of interface pressures as a wheelchair user sits directly on a conventional sling.
One reason why wheelchair users sit directly on the sling is because of their need to reach the ground and propel the wheelchair with their feet, as illustrated in FIG. 3. Such users cannot sit on wheelchair cushions that increase sitting height because they could no longer reach the ground adequately to propel the wheelchair with their feet.